With the advancement of power line network technology, applications thereof have increased in electricity meter and electricity apparatus monitoring, for example, monitoring electricity consumption in a household from a remote office. The Powerline Intelligent Metering Evolution (PRIME) standard adopts a master-slave network topology for the powerline network, where a root node and a plurality of leaf nodes constitute a tree structure, in which there are also switch nodes which serve as relay points between the root node and the leaf nodes. Transmission between the leaf nodes must be conducted through the master node, leading to heavy network traffic loading at the root node and traffic congestion across the master-salve tree network. When a branch node malfunctions, all nodes successive to the broken node may be seriously affected.